Circuit interrupter



J. MAJCHER ETAL Oct. 3, 1967 CIRCUIT INTERRUPTER Filed Oct. 16, 1964 4 Sheets-Sheet 1 mt mm INVENTORS John Mojcher and B'Y Robert H. Flic k ATTORNEY Oct. 3, 1967 J,- M H ETAL 3,345,481

CIRCUIT INTERRUPTER Fi led Oct. 16, 1964 4 Sheets-Sheet 2 Oct. 3, 1967 J. MAJCHER ETAL CIRCUIT INTERRUPTER 4 Sheets-Sheet 3 Filed Odt. 16, 1964 Filed (Jet. 16, 1964, Ser. No. 404,414 4 Claims. (Cl. 200-114) This application is a continuation-in-part of the copending application Ser. No. 197,971, filed May 28, 1962.

This invention relates generally to circuit interrupters and more particularly to circuit interrupters of the type comprising a low-cost circuit breaker and a fuse unit electrically connected in series relation with the circuit breaker to interrupt fault currents that exceed the interrupting capacity of the circuit breaker.

An object of this invention is to provide an improved compactly constructed circuit interrupter comprising a circuit breaker and a fuse unit connected in electrical series with the circuit breaker.

Another object of this invention is to provide a multipole circuit interrupter comprising a multi-pole circuit breaker and a multi-pole fuse unit connected in electrical series with the circuit breaker with improved means for tripping the circuit breaker upon removal of the fuse unit.

Another object of this invention is to provide a multipole circuit interrupter comprising a multi-pole circuit breaker and a multi-pole fuse unit connected in electrical series with the circuit breaker with improved means for tripping the circuit breaker when one of the fuses of the fuse unit blows.

Another object of this invention is to provide a multipole circuit interrupter comprising a multi-pole circuit breaker and a multi-pole fuse unit connected in electrical series with the circuit breaker with improved means for preventing operation of the circuit interrupter if one of the fuses is not in place in the fuse unit.

1 Another object of this invention is to provide an improved fuse unit comprising improved means for positioning the fuses in the fuse unit housing.

' A more general object of this invention is to provide an improved circuit interrupter which largely retains the advantages of circuit breakers over fuses and at the same time embodies the desirable current-limiting function of current-limiting fuses when there is a heavy short circuit, without requiring the use of an expensive circuit breaker of high interrupting capacity.

The invention, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description when read in conjunction with the accompanying drawings.

In said drawings:

FIGURE 1 is a top plan view of a circuit interrupter embodying principles of this invention;

FIG. 2 is a side elevational View, with parts broken away, of the circuit interrupter seen in FIG. 1;

FIG. 3 is a sectional view of the removable fuse unit taken generally along the line III-III of FIG. 1;

- FIGS. 4 and 5 are elevational and end views, respectively, of the barrier and tripping spring seen in FIGS. 1 and 2;

FIG. 6 is a top plan view of the tripping bar seen in FIG. 1;

FIG. 7 is an end view of the tripping 6 looking in the direction of the arrows;

FIG. 8 is a top plan view of the trip bar seen in FIG. 1; FIG. 9 is a sectional view taken along the line IXIX of FIG. 8;

FIG. 10 is a View similar to FIG. 1 of a circuit breaker embodying a modifiedform of the .invention;

bar seen in FIG.

United States Patent 0 (not shown) that is mounted 3,345,481 Patented Oct. 3, 1967.

FIG. 11 is a top plan view of the two support plates and trip bar that are shown in broken lines in FIG. 10;

FIG. 12 is a side elevational view of the parts seen in FIG. 11 with the parts being shown prior to the mounting thereof in the circuit interrupter;

FIG. 13 is a sectional view taken generally along the line XIII-XIII of FIG. 10;

FIG. 14 is a side sectional view illustrating certain parts of the circuit interrupter of FIGS. 10 and 13;

FIG. 15 is a top plan view of some of the parts seen in FIG. 14;

FIG. 16 is a bottom FIGS. 10 and 13; and

FIG. 17 is a sectional view taken generally along the line XVII-XVII of FIG. 16.

Referring to the drawings, and particularly to FIGS. 1 and 2, there is shown therein a circuit interrupter 3 comprising a multi-pole circuit breaker 5 and a removable multi-pole fuse unit 7 connected in electrical series with the circuit breaker 5. The circuit breaker 5 comprises a housing comprising an insulating base 11 and an insulating cover 13 suitably connected to the base 11. A circuit breaker mechanism 14, of the type disclosed in Patent No. 2,989,606, issued June 20, 1961, to E. J. Walker et al., is supported within the housing 11, 13.

Each pole unit of the circuit interrupter 3 comprises a line terminal 15 and a load terminal 17 to enable connection of the circuit interrupter in an electrical circuit. A solderless terminal conductor 18 is disposed at the cutter end of each of the terminals 15, 17 in a manner well known in the art.

The circuit breaker 5 is of the three-pole type, only the center pole being shown in FIG. 2. An operating mechanism 19 common to all of the poles, is disposed in the center pole compartment. Each pole is provided with a trip device 21 similar to that seen in FIG. 2.

A stationary contact 22 is rigidly mounted on the inner end of each of the terminal conductors 17. A movable contact 23 is provided to cooperate with each of the stationary contacts 22. Each of the movable contacts 23 is secured to a movable contact arm 25 that is pivotally mount-ed by means of a pin 29 on a switch arm 31. The switch arms 31 for the three pole units are secured to a common insulating tie bar 35 that is rotatably supported in the circuit breaker housing 11, 13. Springs (not shown) bias the contact arms 25 clockwise about the pins 29 to provide contact pressure in the closed position of the contact arms.

The operating mechanism 19 is disposed in the center pole unit and comprises a U-shaped operating lever 41 having its inner end portions pivoted on a suitable frame on the base 11. The operating lever 41 has an arcuate shield 47 mounted on the outer end thereof. A handle portion 49 extends out from the shield 47 through an opening 51 in the cover 13. The switch arm 31 for the center pole unit is operatively connected, by means of a toggle comprising links 53 and 55, to a releasable member or cradle 57 that is pivotally mounted on a pin 59 that is supported in the frame that supports the lever 41. The toggle links 53 and 55 are pivotally connected together by a knee pivot pin 61. The toggle link 53 is pivotally connected to the releasable member 57 by a pivot pin 63, and the toggle link 55 is pivotally connected by means of a pin 65 to the switch arm 31 for the center pole. Overcenter springs 67 are connected under tension between the knee pivot pin 61 of the toggle 53, 55 and the yoke portion of the U-shaped operating lever 41.

The contacts for all of the poles are manually closed and opened in a well-known manner by movement of the operating lever 41 to the on' and off positions. Moveplan View of the trip unit seen in ment of the lever 41 to the on position straightens the 9 toggle 53, 55 to move the switch arm 31 for the center pole unit to the closed position. Since the switch arm for the center pole unit is connected to the tie bar 35, this movement rotates the tie bar 35 clockwise (FIG. 2) to move all of the switch arms 31 to the closed position. Reverse movement of the operating lever 41 to the off position causes collapse of the toggle 53, 55 to rotate the tie bar 35 counterclockwise and move all of the switch arms 31 to the open position.

The contacts are opened automatically, in response to an overload current above a predetermined value in any pole of the circuit breaker, by release of the cradle or releasable member 57. The cradle 57 is normally releasably held in an operative position by means of a latch mechanism indicated generally at 71 which is actuated by the trip device 21 to release the cradle 57. When released, the cradle 57 rotates clockwise about its pivot 59 under the influnce of the overcenter springs 67 causing collapse of the toggle 53, 55 to move all of the switch arms 31 to the open position.

The latch mechanism 71 comprises a main latch 73 that is pivoted on a pin 75 that is supported in the frame that supports the lever 41. The main latch 73 is biased by a Spring 77 in a clockwise unlatching direction. The main latch 73 is provided with a latching portion 79 that engages a latch portion 81 on the free or latching end of the cradle 57 to releasably hold the cradle in the operative position. The latch portion 81 is in-turned and faces generally toward the pivot 59 about which it moves. The main latch 73 is releasably held in latching position by a latch that comprises a rotary shaft 83 that is pivotally mounted on the supporting frame. The main latch 73 is held in the latching position by the engagement of a part thereof with the shaft 83. This engagement is at a point on the cylindrical surface of the shaft 83 adjacent a notch (not shown) in the shaft 83. The purpose of the notch Will be hereinafter specifically described. The latch 83 has an upwardly extending arm portion 89. An adjusting screw 93, which is threaded on the arm 89, is movable into engagement with a projection 97 on a common trip bar structure 98. The arm 89 and rotary shaft 83 are biased by spring means to the latching position seen in FIG. 2. v

The trip bar structure 98 comprises a trip bar 99 that is of molded insulating material. The projection 97 is molded integral with the trip bar 99 at a position adjacent the adjusting screw 93. The trip bar 99 is rotatably supported in the housing 11, 13 by means of pins 101 (FIG. 8) molded in the ends thereof. Three projections 103, one for each pole unit, are molded integral with the trip bar 99.

The trip device 21 for each pole unit comprises a bimetal 105 that is supported on a conducting tab 107 by means of a screw 109. An adjusting screw 113 is threaded in a tab that is attached to the free end of the bimetal 105, and a generally U-shaped magnet member 115 is secured to the bimetal 105 intermediate the ends of the bimetal. A magnet member 117 is also connected to the conducting tab 107 by means of the screw 109. A leaf spring 119 having a contact 121 thereon is secured to the member 117 for a purpose to be hereinafter specifically described. A flexible conductor 123 is secured at one end to the bimetal 105, and at the other end to a terminal 125.

When a low persistent overload current occurs in any pole unit, the current carrying bimetal 105, for that pole unit, becomes heated and when heated a predetermined amount bends to the right. This movement, through the adjusting screw 113 and projection 103, rotates the trip bar 99 in a clockwise direction causing the projection 97 thereon to rotate the arm 89 and the rotary latch 83 clockwise until the latch 83 reaches a point where a portion of the main latch 73 snaps into the notch in the main latch 83 under the force of the springs 67. This movement releases the cradle or releasable member 57, whereupon the member 57 is rotated clockwise by means of the springs 67 to cause collapse of the toggle 53, 55 and opening of all of the contacts 22, 23.

The circuit breaker is trip-free in that the mechanism will operate to open the contacts when a tripping overload occurs even if the handle 49 is held in the closed position.

Upon the occurrence of an excessive overload current or a short circuit current, the magnet member is attracted to the magnet member 117 bending the bimetal 105 to rotate the trip bar 99 to effect instantaneous tripping of the breaker. This bending of the bimetal 105 closes a contact (not shown) near the top of the bimetal 105 with the contact 121 that is supported on the leaf spring 119 forming a parallel shunt path for the current through the breaker. Since the resistance of the shunt path through the members 119 and 117 is less than the resistance through the bimetal 105, the major part of the current will be shunted around the bimetal, thus preventing overheating of the bimetal. By proper adjustment of the magnetic air gap and the distance between the shunting contacts, these contacts will close only on magnetic tripping and the breaker will trip on thermal tripping without closing the shunting contacts so that the thermal trip calibration is not affected by the shunting contacts.

Before the breaker contacts can be closed following an automatic opening operation, it is necessary to reset and relatch the mechanism. This is accomplished by moving the handle 49 counterclockwise to a position slightly past the full off position. During this movement, a projection 125 on the operating lever 41 engages a shoulder 127 on the cradle 57 to move the cradle counterclockwise about its pivot 59. Near the end of this movement, the lower rounded portion of the latch end 81 of the cradle 57 engages an outwardly extending portion of the bell-crank type main latch 73 to move the main latch 73 to the latching position. As soon as the latching shoulder of the main latch 73 clears the corner of the notch (not shown) of the cylindrical latch 83, a torsion spring restores the arm 89 and latch 83 to the normal latching position. The latching port-ion 79 of the latch 73 is then above the latch end 81 and it engages the latch end 81 of the cradle 57 to hold the cradle in the operative latched position seen in FIG. 2. Thereafter, the contacts can be closed and opened by operation of the handle 49 in the same manner previously described.

The multi-pole fuse unit 7 (FIGS. 13) comprises a housing 131 of molded insulating material which housing comprises three compartments. A fuse 133 is removably mounted in each of the fuse compartments. Each of the fuses 133 has a conducting member 135 connected to one end thereof and a conducting member 137 connected to the other end. A plug-in type connector 139 is connected to the conductor 135, and a plug-in type connector 141 is connected to the conductor 137. A spring-loaded plunger or actuator 145 is disposed at one end of each of the fuses 133. The plunger 145 is biased to move toward the right when the fuse blows. This plunger and biasing means for operating it may be in one of the forms disclosed, for example, in the patent to Rawlins et al., Patent No. 2,435,844, issued Feb. 10, 1948.

The fuse unit 7 also comprises a tripping bar structure 147 (FIGS. 1-3, 6, and 7), that is rotatably supported in the fuse unit housing 131 and is common to all three poles of the fuse unit. The tripping bar structure 147 is rotatably supported in notches in barriers (not shown) that separate adjacent poles in the fuse unit. Refer-ring to FIGS. 6' and 7, the tripping bar structure 147 comprises an insulating tripping bar 149 having three arms 151 riveted thereto. An actuating arm 153 is riveted to the tripping bar 149 in a position adjacent an arm 155 (FIGS. 1 and 8) of the trip bar structure 98. As is seen in FIG. 3, a spring 157 is supported between the housing 131 and the arm 153 to bias the tripping ba-r structure 147 in a clock- Wise (FIG. 3) direction. This clockwise movement of the tripping bar structure 147 is limited by engagement of the arm 153 with one of the fuses 133.

With the fuse unit 7 in place and the contacts 22, 23 in the closed position, the circuit through each pole unit of the multi-pole circuit interrupter 3 extends from the line terminal (FIG. 2) through a tulip-type connector 163 that is mounted on the base 11, the plug-in type connector 139, the conductor 135 (FIG. 3), the fuse 13-3, the conductor 137, the plug-in type connector 141, a tulip-type connector 165 (FIG. 2) that is mounted on the base 11, the conductor 125, the flexible conductor 123, the bimetal 105, the conducting support 107, a flexible conductor 167, the switch arm 31, the contact arm 25, the contacts 23, 22, to the load terminal conductor 17.

When a fuse 133 in any of the poles blows in response to a severe overload current, biasing means (not shown) within the fuse operates to move the plunger 145 (FIG. 3) to the right against the associated arm 151 to rotate the tripping bar structure 147 counterclockwise against the bias of the spring 157. During this movement, the arm 153 (FIGS. 1, 3, 6 and 7) on the tripping bar 149 engages the arm 155 (FIGS. 1, 8 and 9) on the common trip bar 99 (FIG. 1) rotating the trip bar 99 in a clockwise (FIG. 2) direction, whereupon the projection 97 on the trip bar 99 operates to move the arm 89 and the latch 83 clockwise to effect a tripping operation of the circuit breaker 5 in the same manner hereinbefore described. The plunger or actuator 145 of the blown fuse 133 will remain in the position holding the tripping bar 149 in the tripped position to thereby hold the trip bar 99 and, therefore, the latch 83 in the tripped position. The circuit breaker cannot be relatched, and, therefore, it cannot be operated while the fuse unit, with a blown fuse therein, is in the connected position.

Improved means are provided for tripping the circuit breaker 5 when the fuse unit 7 is removed, and also for maintaining the breaker 5 in the tripped position when the fuse unit 7 is removed if the breaker has been tripped prior to removal of the fuse unit 7. Referring to FIGS. 1, 2, 4 and 5, an insulating barrier 171 which is provided to insulate part of the fuse unit 7 from the parts of the circuit breaker 5, is supported in suitable slots molded in the housing base 11. A metallic leaf spring 173 is mounted on the barrier 171 by means of rivets 175. As can be seen in FIG. 2, a projection 177 having a cam surface 179 thereon is molded integral with the insulating housing 131 of the fuse unit 7. When the fuse unit is moved down into the'connected position seen in FIG. 2, the cam surface 179 on the projection 177 engages the leaf spring 173 to bias the leaf spring 173 to the inoperative position shown. When the fuse unit 7 is removed from the circuit breaker 5, the leaf spring 173 is released whereupon it springs to the right (FIG. 2) to engage an arm 181 (FIGS. '1 and 8) that is attached to the trip bar 99, rotating the trip bar 99 clockwise (FIG. 2) to effect tripping of the circuit breaker 5 in the same manner hereinbefore described if the circuit breaker 5 is in the closed position when the fuse unit 7 is removed. If the breaker 5 is in the open position when the fuse unit 7 is removed, the leaf spring 173 will move against the arm 1 81 to rotate the trip bar 99 clockwise to release the -mechanism 19 to the tripped position to prevent closing of the breaker. As long as the fuse unit is removed, the spring 173 will maintain the trip bar 99 in the tripped position to prevent relatching of the breaker to thereby prevent a closing operation of the breaker. If the breaker 5 is in the tripped position when the fuse unit 7 is removed, the spring 173 biasing against the arm 181 will maintain the trip bar 99 in the tripped position to prevent relatching of the circuit breaker 5 to thereby prevent a closing operation of the circuit breaker.

If the fuse unit 7 should be placed in position on the interrupter with a blown fuse still in the holder, the plunger or actuator 145 (FIG. 3) would hold the tripping bar structure 147 in a tripping position, and the arm 153 on the tripping bar structure 147 would engage the arm 155 (FIG. 1) on the trip bar 99 to bias the trip bar 99 to the tripped position to prevent resetting of the circuit 6 breaker 5. Thus, when the spring 173 (FIG. 2) is biased to an inoperative position, the arm 153 on the tripping bar structure 147 will take over to maintain the trip bar 99 in the tripped position. Thus, the circuit interrupter cannot be operated when the fuse unit is replaced if the blown fuse is still in the fuse unit.

In order to facilitate removal of the fuse unit 7 from the circuit breaker 5, the fuse unit housing 131 is molded with two projections 185 on one side thereof and a projection 187 on the opposite side. As can be seen in FIGS. 1 and 2, the projections 185 are disposed over openings 189 in the housing which openings are provided to accommodate two of the terminals 1'9. The projection 187 is disposed over a depression or well-portion 191 in the housing. Thus, a worker can grasp the projections 185 and 187 with his fingers to lift the fuse unit 7 out of the circuit interrupter. The housing adjacent the depression or well-portion 191, can also be used as a fulcrum for a screwdriver or similar lever to lift housing 131. As can be seen in FIG. 2, when the fuse unit 7 is in the connected position, two plug-in type connectors 139, 141 engage in two tulip-connectors 163, respectively, for each of the pole units. These connections are provided to have sufficient pressure to insure good electrical conductivity. Thus, it is often difiicult for a worker to remove the fuse unit 7 from the circuit breaker 5 by grasping the projections and 187. Improved means, therefore, are provided to facilitate removal of the fuse unit 7 from the circuit interrupter when a worker has difiiculty in removing the fuse unit by grasping and lifting on the projections 185, 187.

Referring to FIGS. 1 and 2, two bolts 193 pass through suitable openings in the fuse unit 7 and are threaded into tapped metallic inserts 195 in the housing base 11 to secure the fuse unit 7 to the circuit breaker. When removal of the fuse unit 7 in the manner hereinbefore described is difiicult, the bolts 193, which are removed from their mounting positions, are threaded into tapped metallic inserts 197 in the fused unit housing 131. As can be seen in FIG. 2, the inserts 195 are so positioned that the major portion of each of the bolts 193 extends out ward from the fuse unit 7 to permit easy grasp thereof by a worker who can grasp one bolt with each hand to lift the fuse unit 7 out of place. The bolts 193 can also be grasped by means of a suitable tool to enable a worker to more easily remove the fuse unit 7 from the circuit breaker 5.

Another embodiment of the invention is disclosed in FIGS. 10-17. There is disclosed in FIGS. 10 and 13 a circuit interrupter 3a that is similar to the circuit interrupter 3 of FIGS. 1 and 2. The parts (FIGS. l0l7) of the circuit interrupter 3a that are similar to the parts (FIGS. l-9) of the circuit interrupter 3 are identified by reference characters each of which reference characters comprises a small a sufiix after a numeral that is identical to the numeral of the similar part disclosed in the circuit interrupter 3. Because of the similarity between the circuit interrupters 3 and 3a, only those parts that are substantially different will be specifically described, it being understood that unless otherwise set forth the parts of the circuit interrupter 3a function in the same manner as those previously described with respect to the circuit interrupter 3. The circuit breaker 5a is a circuit breaker of the type that is described in more detail in the patent to Charles R. Paton et al., Patent No. 3,303,441, issued Feb. 7, 1967. i

Referring to FIGS. 1013, there is shown therein two side plates 201 and 203 that support certain parts of the circuit breaker mechanism. The side plates 201 and 203 are provided with lower leg portions 205 (FIG. 12) that arepassed through openings in the insulating base 11a and riveted over at 206 (FIG. 13), which operation fixedly mounts the side plates in the center pole unit of the multipole circuit interrupter 3a. The shaft 83a extends through openings in the side plates 201 and 203, and insulating members 207 and 209 are fixedly secured to opposite ends of the shaft 83a in the two outer pole units. The notch 211 which receives part of a main latch 73a during a tripp-lng operation, is visible in FIG. 13. During thermal tripping operations, the bimetal 105a which is heated by the current flowing therethrough, deflects to the right to engage the member 89a (or one of the members 207 or 209 if the overload is one of the two outer pole units) to rotate the shaft 83 in a clockwise (FIG. 13) direction to move the notch 211 adjacent a part 212 of the latch 73 whereupon the latch part 212 snaps into the notch 207 to release the trip member 57 to effect a tripping operation in the same general manner hereinbefore described. A generally V-shaped magnet yoke 215 is supported on a rigid conductor 217 and the two legs of the yoke extend on pposite sides of the bimetal 105a. An armature structure 219, which is pivotally supported at 221 on a supporting plate 223, comprises a magnetic armature 225 that is attracted to the yoke 217 upon the occurrence of short circuits or severe overloads to effect a magnetic tripping operation. Upon the occurrence of an excessive overload or short circuit the electromagnet 217, 225 is energized sufficiently to attract the armature 225 to the yoke 217 pivoting the armature structure 219 in a clockwise (FIG. 13) direction. During this movement, an upper part 229 of the armature structure 219 engages the lever 89 (or one of the members 207, 209 if the overload is in one of the two outer pole units) to rotate the shaft 83 in a clockwise (FIG. 13) direction to effect tripping operation in the same manner as was hereinbefore described.

As can be seen in FIGS. l012, a trip arm 233 is fixedly mounted on the member 207 in one of the outer pole units. The members 83, 89, 207, 209 and 233 (FIG. 11) cooperate to form a unitary trip bar structure 234. When the parts of the circuit interrupter 3a are mounted in position, the trip arm 233 is disposed adjacent an actuating arm 237 (FIG. 13) that is fixedly secured to the tripping bar 149a of the tripping bar structure 147a. The actuating arm 237 of the tripping bar structure 147a is disposed in the outer pole unit of the tripping bar structure 147a and adjacent the plunger 145a of the fuse 133a in the outer pole unit. In each of the two other pole units, an arm 241 is mounted on the tripping bar 149 and disposed adjacent the associated plunger 145a of the associated fuse 133a.

When a fuse 133a in any of the three 'pole units is actuated in response to a severe overload current, biasing means (not shown) within the fuse operates to move the associated plunger 145a against the associated actuating arm 237 or 241 to rotate the tripping bar structure 1471; in a counterclockwise (FIG. 13) direction against the bias of the spring 157a. During this movement, the actuating arm 237 of the tripping bar structure 147a engages the arm 233 to rotate the trip bar structure 234 to a tripped position moving the shaft 83 in a clockwise (FIG. 13) direction to effect a tripping operation of the circuit breaker 5a in the same manner hereinbefore described.

If the fuse unit 7a should be 'placed in position with an actuated fuse still in the holder, the plunger 145a of the actuated fuse would still engage the associated actuating arm 237 or 241 to maintain the tripping bar structure 147 in the actuated tripping position thereby providing that the member 237 would engage the arm 233 to hold the trip bar structure 234 in the tripped position.

In each pole unit of the fuse unit 7a, a leaf spring 245 is secured to the housing 131a by means of a screw 247. In each pole unit, an actuating member 249, which is fixedly secured to the outer end of the associated leaf spring 245, engages the associated fuse 133a to maintain the resilient leaf spring 245 in a fixed charged condition. When the associated fuse 133a is removed from the housing 131a the fuse 133a moves away from the associated member 249 releasing the spring 245. The released spring defects toward a straightened position during which movement the outer end of the spring 245 engages a tail portion 253 (FIG. 13) on the associated actuating arm 237 or 241 to rotate the tripping bar structure 147 in a counterclockwise (FIG. 13) direction to provide an engagement between the member 237 and the arm 233 that will maintain the trip bar structure 234 in the tripped position with the shaft 83 in the unlatching position. With the shaft 83a in the unlatching position the circuit breaker 5a cannot be reset into the operating position. Thus, the missing fuse interlock 245, 249, 253 provides that the circuit interrupter 3 cannot be operated when a fuse is missing from the removable fuse unit 7a.

The same actuating arm 237 on the tripping bar structure 147a cooperates with the same member 233 on the trip bar structure 234 when any of the fuses is actuated or when any of the fuses is missing from the fuse unit 7.

Referring to FIGS. 10, 13, 16 and 17, the fuse unit 7a comprises the housing 131a of molded insulating material which housing comprises three compartments separated by means of insulating barriers 257 (FIGS. 16 and 17) that are molded integral with the housing part 131. Each of the barriers 257 is provided with an opening 259 (FIG. 17) therein to permit mounting of the common tripping bar structure 147a in the fuse unit 7a. After the tripping bar structure 147a is moved into the mounted position, two insulating barriers 261 are moved into the mounted position seen in FIGS. 16 and 17 to substantially close the openings 259 in the barriers 257 and to rotatably support the tripping bar structure 147a in position in the fuse unit 7a. As is illustrated in FIG. 17, each of the barriers 261 is provided with an arcuate notch portion 265 that receives the tripping bar 14911 to rotatably support the tripping bar structure 147a in position. With the tripping bar structure 147a and the three fuses 133a positioned in the three compartments of the insulating housing 131a, all of which members are moved into position from the open bottom of the housing 131a, an insulating support 267 that extends across the bottom of all three pole units of the fuse unit 7a, is moved into position engaging the two barriers 257 and two screws 269 are passed through openings in the support 267 and threaded into tapped openings in the two insulating barriers 257 to'capture the three fuses 133a in position in the insulating housing 131a. Each of the barriers 261 (FIG. 17) is provided with a ledge portion 271 that is engaged by the member 267 to support the barrier 261 and therefore the tripping bar 149 in position.

Referring to FIGS. 13 and 16, it will be noted that there is a generally L-shaped rigid metallic member 273 fixedly secured to the associated conductor 135. A lower leg 275 of the member 273 is disposed in a notch 277 in the insulating housing 131 to prevent rotation (about an axis extending generally between the conductors 135a, 137a) of the associated fuse 133a in the housing 131a. The member 275 also engages the end wall of the housing 131a to prevent generally rectilinear axial movement of the associated fuse 133a in a direction to the left as seen in FIG. 13. The member 267 engages the members 139 to limit movement to the right (FIG. 13) of the fuses 133. There are two arcuate barriers 279 and 281 (FIG. 13) in each of the three compartments of the housing 131 which barriers are molded integral with the housing 131 to limit upward (FIG. 13) movement of the fuses 133a.

Referring to FIGS. 13-15, a metallic leaf spring member 285 is fixedly secured to a ledge part 286 of the base 11 by means of a screw 287 that passes through a suitable opening in a generally flat low part 291 of the member 285 and is threaded into a tapped opening in the ledge part 286. The ledge part 286 of the base 11 is part of one of the barriers that is molded integral with insulating housing base 11 to separate two adjacent pole units of the housing. The leaf spring 285 comprises the generally horizontal base part 291 that receives the screw 287 and a vertical part 293 (FIG. 14) that extends upward from the base part 291. The part 293 is bent over to provide another horizontal part 295 that is generally parallel to-the base part 291. The horizontal part 295 is disposed under the arm 233. The end part of the spring structure 285 extends upward at 297 to provide an upper end that is engaged by the fuse unit housing structure 131a (FIG. 13) to flex the spring structure 285 to a charged lower inoperative position (shown in full lines in FIGS. 13 and 14) when the fuse unit 7a is moved into the connected position seen in FIG. 13. When the fuse unit 7a is removed from the circuit breaker a, the charged resilient leaf spring structure 285 is released whereupon it springs upward from the position in which it is seen in full lines in FIGS. 13 and 14 to the position in which it is seen in broken lines during which movement the horizontal part 295 thereof engages the member 233 to rotate the shaft 83a in a clockwise (FIG. 13) direction moving the trip bar structure 234 to the tripped position to trip the circuit breaker in the same manner herein'before described. While the fuse unit 711 is removed the spring structure 285 will maintain the trip bar structure 234 in the tripped position to prevent operation of the circuit breaker 5a. When the fuse unit 7a is moved into the connected position seen in FIG. 13, a ledge portion 299 on the insulating housing 131a engages the upper part 297 of the leaf spring structure 285 flexing the structure 285 to the full line position seen in FIGS. 13 and 14 to release the arm member 233 to thereby permit a relatching operation of the circuit breaker in the same manner as was hereinbefore described.

From the foregoing, it will be understood that there is provided by this invention an improved compactly constructed circuit interrupter comprising a fuse unit having a common tripping bar structure therein and a circuit breaker having a trip bar structure therein. The fuse unit comprises an insulating housing having a plurality of compartments therein and means fixedly retaining a separate fuse in each of the compartments. When any one of the fuses of the multi-pole fuse unit is actuated, the actuated fuse operates to rotate the common tripping bar structure whereupon the tripping bar structure engages an actuating arm of the breaker trip bar structure to rotate the trip bar structure to a position to effect tripping of the multi-pole circuit breaker. A leaf spring or safety trip member is provided to effect tripping of the circuit breaker when the fuse unit is removed and to maintain the circuit breaker in a tripped position as long as the fuse unit is removed. The leaf spring or safety trip member, which is biased to an inner un'actuated position when the fuse unit is in place, operates automatically when the fuse unit is removed, to directly engage part of the tripping bar structure to rotate the tripping bar structure to trip the circuit breaker.

In one embodiment of the invention the same actuating arm of the trip bar structure is operated to trip the breaker or to maintain the breaker in the tripped position When any of the fuses is actuated; when the fuse unit is removed from the circuit breaker; when the fuse unit is mounted on the circuit breaker with an actuated fuse in the unit; and when the fuse unit is mounted on the breaker with one or more of the fuses missing from the unit.

The circuit interrupter is constructed so that the fuse unit does not extend substantially higher than the highest part of the front surface of the circuit breaker housing. Thus, a fiat panel platepan be placed over the compact circuit interrupter With the handle of the circuit interrupter extending through an opening in the panel plate to enable manual operation of the circuit interrupter.

While the invention has been described in accordance with the provisions of the patent statutes, it is to be understood that various changes and modifications may be made in the structural details and arrangement of parts without departing from the spirit and scope of the invention.

We claim as our invention:

1. A multi-pole circuit interrupting device comprising, in combination, a circuit breaker comprising a first housing, a multi-pole circuit breaker mechanism disposed gen erally within said first housing and comprising separable contact means for each pole, a common unitary trip bar structure comprising a rotatable member and two arm members extending from said rotatable member, means operable upon the occurrence of certain current conditions in any of said poles to rotate said common unitary trip bar structure to effect opening of the contact means in all of said poles, a muiti-pole fuse unit comprising a second housing and fuse unit means supported on said second housing, said fuse unit means comprising a fuse for each pole of said circuit breaker and a common unitary tripping bar structure, each of said fuses comprising means operable upon the occurrence of certain current conditions to operatively move said common unitary tripping bar structure, said common unitary tripping bar structure when operatively moved engaging one of said arms and rotating said common unitary trip bar structure to effect opening of the contact means in all of said poles, means removably connecting said fuse unit to said circuit breaker, said circuit breaker comprising a leaf spring, a portion molded integral with said second housing engaging said leaf spring to bias said leaf spring to an inoperative position when said fuse unit is mounted on said circuit breaker, and upon removal of said fuse unit from said circuit breaker said leaf spring automatically moving to directly engage said other arm to rotate said common unitary trip bar structure to effect opening of the contact means in all of said poles.

2. A multi-pole interrupting prising, in combination, a circuit breaker comprising a first housing, a multi-pole circuit breaker mechanism disposed generally within said first housing and comprising separable contact means for each pole, a common trip bar structure common to all of said poles and operatively movable to a tripped position to effect opening of all of said contact means, a multi-pole fuse unit comprising a second housing, fuse unit means supported on said second housing and comprising a removable fuse for each pole of said circuit breaker and a common tripping bar structure, each of said fuses comprising means operable upon the occurrence of certain current conditions to operatively move said common tripping bar structure to a tripping position, said common trip bar structure comprising a trip arm, said common tripping bar structure when operatively moved to the tripping position engaging said trip arm to operatively move said common trip bar structure to a tripped position to effect opening of all of said contact means, said fuse unit being movably mounted on said circuit breaker, said fuse unit comprising safety trip means at each pole unit thereof mounted on said second housing each of which safety trip means moves automatically to move said common tripping bar structure to the tripping position when the associated fuse is removed from said fuse unit.

3. A multi-pole circuit interrupting device comprising, in combination, a circuit breaker comprising a first housing, a multi-pole circuit breaker mechanism disposed generally within said first housing and comprising separable contact means for each pole, said circuit breaker comprising a common trip bar structure common to all of said poles and operatively movable to a tripped position to effect opening of all of said contact means, a multi-pole fuse unit comprising a second housing, fuse unit means supported on said second housing and comprising a separate removable fuse for each pole of said circuit breaker, said fuse-unit means comprising a common tripping bar structure, each of said fuses comprising means operable upon the occurrence of certain current conditions to operatively move said common tripping bar structure to a tripping position, said common device comprising, in comtripping position engaging and operatively moving said common trip bar structure to said tripped position, means removably connecting said fuse-unit to said circuit breaker, said circuit breaker comprising a resilient safety trip member, said fuse-unit comprising means holding said safety trip member in an inoperative position when said fuse-unit is mounted on said circuit breaker, upon removal of said fuse unit said resilient safety trip member engaging said trip arm to operatively move said common trip bar structure to said tripped position, said fuse unit comprising safety trip means at each pole unit mounted on said second housing each of which safety trip means is operable to maintain said common tripping bar structure in said tripping position when any of the fuses in said fuse unit is removed.

4. A multi-pole circuit interrupter device comprising, in combination, a circuit breaker comprising a first housing, a multi-pole circuit breaker mechanism disposed generally within said first housing and comprising separable contact means for each pole, at common trip bar structure movable to a tripped position to effect opening of all of said contact means, means operable upon the occurrence of certain current conditions in any of said poles to operate said common trip bar structure to the tripped position, said common trip bar structure comprising, a trip arm, a multi-pole fuse unit comprising a second housing and fuse unit means supported on said second housing, said fuse unit means comprising a removable fuse for each pole of said circuit breaker and a common trip- 30 ping bar structure, upon rotation of said common tripping bar structure to a tripping position means on said common tripping bar structure engaging said trip arm to move said common trip bar structure to the tripped position, each of said fuses comprising means operable upon the occurrence of certain overload current conditions to operatively move said common tripping bar structure to said tripping position, means removably connecting said fuse unit to said circuit breaker, said circuit breaker com-,

prising resilient means engageable by said fuse unit and held in an inoperative position When said fuse unit is mounted on said circuit breaker, upon removal of said fuse unit from said circuit breaker said resilient means operating automatically to engage said trip arm to move said common trip bar structure to the tripped position, said fuse unit comprising resilient safety trip means in each pole unit mounted on said second housing each of which safety trip means is maintained in a charged in operative position by the associated fuse, and upon the removal of any of said fuses associated resilient safety trip means being automatically released to engage the said common tripping bar structure to move said common tripping bar structure to the tripping position.

References Cited UNITED STATES PATENTS 2,962,568 11/1960 Gaskill 200-133 3,009,038 11/1961 Dorfman 200-114 3,116,385 12/7963 Scott 2001 14 3,118,991 1/1964 Scott ZOO-114- 3,171,002 2/1965 Kinnear 200-433 BERNARD A. GILHEANY, Primary Examiner.

H. A. LEWI'ITER, Assistant Examiner. 

2. A MULTI-POLE INTERRUPTING DEVICE COMPRISING, IN COMPRISING, IN COMBINATION, A CIRCUIT BREAKER COMPRISING A FIRST HOUSING, A MULTI-POLE CIRCUIT BREAKER MECHANISM DISPOSED GENERALLY WITHIN SAID FIRST HOUSING AND COMPRISING SEPARABLE CONTACT MEANS FOR EACH POLE, A COMMON TRIP BAR STRUCTURE COMMON TO ALL OF SAID POLE AND OPERATIVELY MOVABLE TO A TRIPPED POSITION TO EFFECT OPENING OF ALL OF SAID CONTACT MEANS, A MULTI-POLE FUSE UNIT COMPRISING A SECOND HOUSING, FUSE UNIT MEANS SUPPORTED ON SAID SECOND HOUSING AND COMPRISING A REMOVABLE FUSE FOR EACH POLE OF SAID CIRCUIT BREAKER AND A COMMON TRIPPING BAR STRUCTURE, EACH OF SAID FUSES COMPRSING MEANS OPERABLE UPON THE OCCURRENCE OF CERTAIN CURRENT CONDITIONS TO OPERATIVELY MORE SAID COMMON TRIPPING BAR STRUCTURE TO A TRIPPING POSITION, SAID COMMON TRIP BAR STRUCTURE COMPRISING A TRIP ARM, SAID COMMON TRIP BAR STRUCTURE WHEN OPERATIVELY MOVED TO THE TRIPPING POSITION ENGAGING SAID TRIP ARM TO OPERATIVELY MOVE SAID COMMON TRIP BAR STRUCTURE TO A TRIPPED POSITION TO EFFECT OPENING OF ALL OF SAID CONTACT MEANS, SAID FUSE UNIT BEING MOVABLY MOUNTED ON SAID CIRCUIT BREAKER, SAID FUSE UNIT COMPRISING SAFETY TRIP MEANS AT EACH POLE UNIT THEREOF MOUNTED ON SAID SECOND HOUSING EACH OF WHICH SAFETY TRIP MEANS MOVES AUTOMATICALLY TO MOVE SAID COMMON TRIPPING BAR STRUCTURE TO THE TRIPPING POSITION WHEN THE ASSOCIATED FUSE IS REMOVED FROM SAID FUSE UNIT. 